Engine ignition system



-Oct. 25 1938. A. LINSIELL 7 2,134,053.

ENGIHE IGNITION SYSTEM Filed May 11, 1955 l I'- IIIIIII 7 INVENTOR ALf RED A. SELL v ATTORNEY Patented Oct. 25, 1938 UNITED STATES PATENT OFFIQE ENGINE IGNITION SYSTEM Alfred Aubyn Linsell,

Sydcnham, London, England, assignor to Radio Corporation of America, a corporation of Application May 11,

Delaware 1935, Serial No. 20,900

In Great Britain June 2'7, 1934 1 Claim.

ference which would otherwise be caused by the ignition system with nearby radio apparatus.

As is well known radio receiving apparatus is likely to be subjected to considerable interference if situated too near the ignition system of an internal combustion engine and this difficulty becomes very serious in some cases, notably where radio receivers are fitted to motor cars or upon aeroplanes.

There are many known expedients whereby interference by an internal combustion engine ignition system with nearby radio apparatus may be reduced or eliminated and in a number of systems, resort is made to the use of suppressor resistances, for example, resistances in series in the leads to the sparking plugs, there being usually a resistance placed in series in each lead and as near as possible to each plug. It has been found that known systems of this kind have the disadvantage that the series resistances, if of suilicient value to be eifective, tend to make the internal combustion engine difiicult to start, and the object of the present invention is to obviate this difilculty.

According to this invention in its broadest aspect, an ignition system of the kind wherein interference with nearby radio apparatus is reduced or eliminated by means including one or more suppressor resistances is characterized by the provision of means for short circuiting said resistance or resistances so that when the engine is to be started up the said resistance or resistances may be short circuited, but when the engine is running the short circuit or circuits may be removed.

In one preferred class of-arrangement in accordance with this invention the short circuiting means is or are automatically operated so that the short circuit or circuits is or are removed automatically when the engine is running.

In another preferred class of arrangement in accordance with this invention, said short circuit means is or are interlocked with a device '50 which is operated for starting the engine so that performing of an operation necessary for starting the engine is accompanied by a short circuiting of the resistance or resistances.

Fig. 1 shows the invention as applied to a plug, Figs. 2 and 3 show the invention adapted for simultaneous operation with an electric starter.

The inventionwill now be particularly described with reference toits application to ignition systems embodying suppressor resistances in series in ignition leads and adjacent sparking plugs. It is to be understood, however, that the application of the invention is not limited to such ignition system for it may be applied to short circuit (when starting) suppressor resistances placed elsewhere in an ignition system e. g. on one or both sides of the ignition distrib-utor.

The invention is illustrated in the accompanying diagrammatic drawing.

Referring to Figure 1 which shows one way of carrying out this invention, there is provided a suppressor resistance 3 and thermostat switch unit in connection with each spark plug I. The resistance which is diagrammatically represented by a zigzag line is carried upon a former or carrier C which has a terminal T at one end and is adapted at the other to fit over a sparking plug stem, the terminal being connected to the upper end of the resistance and the sparking plug terminal 20 being connected by lead C to the other end of the resistance. Also connected as by lead 2| to the end of the resistance adjacent T and also carried by the former or carrier is a contact 4 adapted to co-operate with another contact 5 carried upon a bi-metallic strip 2 which is arranged parallel to the said former C and. is of about the same length. The bi-metallic strip (like the former or carrier 0) is provided at the end remote from the contacts with an aperture adapted to be passed over the stem of a spark plug, the Whole arrangement being such that the resistance and bi-metallic strip unit may be clamped in position upon the sparking plug stem, as shown, by the ordinary screw terminal 22 thereof.

The ignition or high tension lead 23 is connected, not to the sparking plug terminal but to the terminal T.

The bi-metallic strip is so constructed that at normal atmospheric temperatures the two contacts 4, 5, touch and the resistance is accordingly short circuited. When, however, the engine has been running a sufficient time the rise in temperature will cause the bi-metallic strip 2 to bend, the contacts .4, 5, will open and the short circuit across the resistance 3 will be removed.

In another way of carrying out this invention illustrated in Fig, 2 switches each having contacts adapted to short circuit a resistance 3 in series in the ignition lead to a plug of an internal combustion engine, are arranged to be operated electro-magnetically by electro-magnets EM either as shown by current flowing through a starting motor SM for the engine or through a relay circuit for controlling the energization of the starting motor of the engine. The arrangement is such that whenever the circuit of the starting motor is closed or whenever a relay circuit for the starting motor is closed, the switches are operated to short circuit the resistances, the short circuits being, of course, automatically removed when the starting motor or the control circuit therefor is opened. In Fig, 2 which illustrates the case where the starter motor current operates the switches the starter button is shown as the usual spring biassed button ll having starting contacts SC and the starter battery is marked P. Only one of the suppressor resistances and the associated short circuiting switches is illustrated in Fig. 2 only the magnets EM of the others being shown and the operating members SW of the switches. The switches and resistances may, however, be arranged much as shown in Fig. 3 (to be described) in which case the members SW of Fig. 2 might be the same as the members S of Fig. 3.

In a modification of the last described arrangement (also not illustrated) instead of employing electroinagnetically operated switch means, there is employed mechanically operated switch means mechanically interlocked with the starter switch or button. 7

Where, the usual case, there is a plurality of sparking plugs each with its own series resistance, it is convenient to arrange for these resistances to be short circuited by a common control member. For example as shown in Fig. 3 each resistance 3 may be arranged upon a former or carrier C which also carries a contact 4 and is associated with a fiat metal spring S having a co-operating contact 5 the arrangement of the former C, resistance 3, spring S, and contacts 4, 5, being generally similar to the arrangement of former C, resistance 3, bi-metallic strip 2,

r and contacts 4, 5, in Fig. l and such that when contacts 4, 5, are closed against the bias of the associated spring S the appropriate resistance 3 is short circuited by the said metal spring. The former-resistance-spring units have terminals T for connection of ignition leads and are arranged to be fitted over and clamped upon the sparking plug stems much as in Fig. 1. Preferably the arrangement is as shown in Fig. 3 so that the springs S project vertically upwards from the plugs l. The springs S are continued beyond the contacts 4, 5, and formers C and have apertures or slots through which pass a control wire or rod I this control wire or rod passing successively through all the springs of all the units and being arranged when pulled in the direction of the arrow to cause each spring S to short circuit its associated resistance 3. The operating rod or wire I should, of course, include insulating portions 8 so that it cannot short circuit one sparking plug to another. The operating rod or wire 1 is controlled by a master lever 9 which may be interlocked with or even constituted by a starter switch (usually a spring biassed press button, and shown as such at H in Fig. 2) so that when the starter switch is operated the resistances 3 are short circuited. As shown the lever 9 is pivoted at Ill and the starter switch contacts are represented at SC. Alternatively the operating rod or wire I may be arranged to be actuated by a bimetallic or other thermostatic device which may be specially provided for the purpose, the device being arranged to hold the resistances short circuited so long as the engine is cold but to be operated by engine heat so that it removes the short circuits when the engine is warm. Where an embodiment of this kind is applied to an automobile which is already equipped with a thermostatic device for operating louvres or ventilators in connection with the cooling water system of the engine or for operating a baflie valve in connection with said cooling water the same thermostatic device may be employed for operating the short circuiting switch or switches. Again in a further modification (not illustrated) the control rod or wire is operated by an electro-magnet energized either under the control of a thermometer switch (i. e., a temperature operated switch) associated with thecooling water of the engine, or in dependence upon current flowing through the starter motor or a relay circuit therefor so that when the motor circuit or the relay circuit therefor is energized the resistances are short circuited but are in circuit at other times. Instead of employing an electro-magnet to control the short circuits mechanically by means of an operating rod or wire, the control may be electrical i, e., the operating rod or wire may be dispensed with and each spring adapted to serve as the armature of a separate operating electromagnet, all these operating electro-magnets having their windings in series with a source of potential P and the contacts of an electro-magnetic switch whose energization may be controlled in any of the ways just described in connection with an electro-magnet for actuating an operating rod or wire An important practical advantage of the invention is that it enables large resistances to be 'used for radio interference suppression and therefore enables eflicient interference suppression to be achieved, because, of course, the difficulty that large resistances interfere with the starting up of the engine is obviated by the said invention.

Having now particularly described and ascertained the nature of my invention and in what manner the same is to be performed, what I claim as novel and desire to secure by Letters Patent is:

In an electric ignition system for an engine provided with a starting switch and having a plurality of spark plugs, the combination of a resistor connected electrically in series with and extending upwardly from the top of each of said plugs, a conducting spring member connected to the lower end of each of said resistors and normally disengaged from the upper end, a horizontally disposed slide rod connected to the upper ends of said conducting spring members, each portion of the slide rod that is connected to the spring member being electrically insulated from the other such portionsof the slide rod, and mechanical linkage between the starting switch and the slide rod whereby upon actuation of the starting switch the slide rod is moved to urge the normally disengagedends of the conducting 

